By the way: how come I can afford to create a link to the original article, while the BBC and other mass media cannot? Is it really so bloody difficult? Isn’t it just basic good journalism?

Also by the way: I really like getting good suggestions for environmental news stories to blog about… but I love it when people join the Azimuth Forum and post links to these news articles under News and Information.

Some puzzles. Guess before you google:

1) Which nation has the highest carbon emissions per person? In 2007 its per capita carbon emissions were almost 3 times that of the USA. I bet it’s still the champion today.

2) Say I make some round-trip flights from Los Angeles to Singapore, with one stop each way. How many flights would it take to burn as much carbon as an average US citizen does in a year? A rough estimate, please!

3) How many such flights would equal the yearly carbon emissions of an average world citizen?

(I am calculating the footprint of a flight using Terrapass. I have no idea how accurate it is or how it works. Also: all my figures only count carbon emissions from burning fossil fuels.)

Very good guess! It’s some place of the sort you describe. My 2007 data lists Kuwait as the fourth biggest producer of carbon emissions per capita. They burned 1.6 times as much carbon as the USA, per person.

Haha. Saudi Arabia? definitely less “politically progressive”, women who commit adultery get decapitated by sword, for men it’s a lot less severe. Of course, in Pakistan, if a women gets raped, her family will kill her to get rid of the shame she has brought to her family… (NPR report some days ago)

No, that’s not it. They actually burn less carbon per capita than the US — or at least they did in 2007.

The country I’m thinking of is ruled by an emir, and political parties are banned, and they follow sharia law. On the other hand women are allowed to vote in municipal elections, and they have a rather famous uncensored radio station. So I guess it’s a mixed bag.

Since nobody seems to want to come out and say the answer, I will give a devastatingly powerful hint that renders the actual answer unnecessary. The first letter of this country’s name is “Q”… but the second letter is not “u”.

I’ve got the magazine from the UK’s Mail on Sunday newspaper in front of me (there was a “free” CD offer, don’t judge me…) It’s got a data graphic of “Carbon emissions” (which I presume means carbon dioxide, methane, …) for some unspecified timeperiod (which unfortunately isn’t online) with unspecified accounting (eg, who counts for importing carbon intensive goods). According to that graphic the largest per capita carbon emitter is Gibraltar, followed by the “Virgin Islands, US” and then probably Qatar, although lots of Middle Eastern countries have per capita emissions of about the same size. The other two blobs about that size are “Trinidad and Tobago” and “Former Netherlands Antilles”.

This seems to be saying that per-capita stats are dominated by tiny population countries, I don’t have any real idea why.

It seems to accord with the “per captia” column in this spreadsheet (referenced by this different newspaper here). There are some odd numbers (Virgin Islands (US) has almost 30 times more emissions per capita than Virgin Islands (Britsh)). I’m tempted to think that it’s a case of having a very small “permanent population” but a large number of highly-consuming tourist visitors relative to size of the population that causes them to have very, very large “per capita” emissions. Of couse, they’re getting money from those visitors so they do derive great benefit, but is it illuminating to assign all that use to their country rather than the tourists country?

Question 2: if the average American owns a car, let’s say one car per capita, which accounts for people who own more than one, and say the average car weight is 2500 pounds, then I’ve heard that each car burns its weight in carbon per year. Double that figure for the total attributable for each citizen for electricity generation, so 5000 pounds of saturated hydrocarbons burned per year per capita.

A flight from LA to Singapore will burn approximately 80,000 pounds of fuel. With a payload of 350 passengers and crew, that comes to about 229 pounds of fuel per person per flight.

5000 pounds/229 pounds = 21.8 flights (roughly 22 flights).

Question 3: how many flights would that be for an average world citizen? The US uses 25% of the world’s fuel, and has 300 million citizens. The world has roughly 7 billion people, so the US has roughly 4.3% of the people in the world.

Great! It’s really good that you’re tackling these things by back-of-the-envelope calculations instead of just looking them up. We can probably learn something by comparing your calculations to the answers I get by just looking them up.

Let’s see…

Terrapass tells me that one round-trip flight from Singapore to Los Angeles, with one stop each way, means I’m creating 7280 pounds of CO2. You said:

A flight from LA to Singapore will burn approximately 80,000 pounds of fuel. With a payload of 350 passengers and crew, that comes to about 229 pounds of fuel per person per flight.

Now, you seem to be doing a one-way flight, while my question was about round-trip flights. So, let’s double your figure and get roughly 450 pounds of fuel.

Also, you’re talking about fuel while Terrapass is talking about CO2. All faithful readers of Azimuth know that to convert from a mass of carbon to the mass of carbon dioxide it forms when you burn it, you multiply by 3.67.

… but this fuel is hydrocarbon, not carbon, so the ratio is less. This website, which I have no particular reason to trust, says that for gasoline the ratio is about 3.33. Airplane fuel might be slightly different, but never mind: your 450 pounds of fuel will burn to give roughly 1500 pounds of CO2.

This is not very close to Terrapass’s figure of 7280 pounds!

So, we’ve learned something. You and Terrapass agree on the order of magnitude, but the difference is substantial. So, at least one of you is making some kind of mis-estimate.

Where did you get your figure of “80,000 pounds of fuel”? You can get a rough sense of how Terrapass did their calculation here. It would, of course, be very interesting if they were way off!

Anyway, for now I will go with their figure and finish answering these puzzles. Terrapass says my round-trip flight produces 7280 pounds of carbon dioxide — or, switching to civilized units, 3,300 kilograms or 3.3 tonnes.

Wikipedia provides data from the US Department of Energy on per capita CO2 emissions in various countries. In 2007, the latest year they cover, the average US citizen emitted 18.9 tonnes of CO2 by burning fossil fuels. You said:

5000 pounds of saturated hydrocarbons burned per year per capita

and this would equal about 17,000 pounds of CO2, or 7.6 tonnes. So your estimate is less than half what the Department of Energy says. Since I doubt the DOE would dramatically overestimate the US carbon footprint — unless it was, like, infiltrated, by, like, liberals — I guess your estimate is too low. It would be interesting to think about why.

By the way, there's no way I could have guessed any of these things, so please don’t take any of what I’m saying as some sort of criticism! I’m just saying there’s probably something in this heuristic:

If the average American owns a car, let’s say one car per capita, which accounts for people who own more than one, and say the average car weight is 2500 pounds, then I’ve heard that each car burns its weight in carbon per year. Double that figure for the total attributable for each citizen for electricity generation, so 5000 pounds of saturated hydrocarbons burned per year per capita.

which is getting an answer less than half the true answer (or at least the DOE answer), and it would be very interesting to know what! Are cars worse than you think, is stuff other than cars worse than you think, or what?

Anyway, I’m getting a US per capita CO2 emission of 18.9 tonnes, while a round-trip flight to Singapore produces 3.3 tonnes. So: if I want to be an average American — as far as CO2 emissions goes — I can take 5.7 round-trip flights from Singapore to LA as long as I don’t produce CO2 in any other way.

How about a ‘world citizen’? For some inane reason the Wikipedia article doesn’t list world per capita CO2 emissions, but they do say that in 2007 the world put out 29 gigatons of CO2. For some other inane reason, Wikipedia doesn’t seem to list world populations year-by-year, but looking at old versions I see the world population in 2007 was about 6.6 billion. So in 2007, the average person emitted 4.4 tonnes of CO2 by burning fossil fuels.

If my roundtrip flight from Los Angeles to Singapore puts out 3.3 tonnes, if I want to be an average citizen of the world — as far as CO2 emissions goes — I can take 1.3 round-trip flights from Singapore to LA as long as I don’t produce CO2 in any other way.

So, I can take one flight, and then .3 of another flight… at which point they’ll have to throw me out of the plane.

“Passenger Baez, passenger Baez, you have used all your carbon rations. Would you please come to the front cabin and step out of the emergency exit?”

Here’s the analysis by Terrapass on fuel burn rates, for a Boeing 777, flying, respectively, 3000 nautical miles (nm) and 3500 nm, namely around 42,000 kg for 3000 nm and 53,000 kg for 3500 nm. This is on page 28 of this document: htttp://carbon.trx.com/TRX_CO2_Emissions_Documentation_v1.4.pdf
which is cited by Terrapass as a reference. 42,000 kg comes out to about 92,000 pounds. I got my WAG (wild-assed guess) figure from a friend who flew 747s and he told me that the average fuel load is 10,000 gallons, and one gallon weighs about 8 pounds.

I estimated the weight of carbon produced, not the weight of CO2, the difference is 32g/mole, so if you burn carbon with 100% efficiency, you get a weight increase from 12g/mole to 44g/mole. A friend’s rule of thumb estimates for automobile emissions is that an automobile generates its weight in carbon per year, thus about 3.7 times its weight in CO2…. so my first WAG was messed up. Take 2500 pounds x 3.7 and that equals about 9250 pounds. I just doubled the auto emissions, setting the amount for all other uses equal to the amount of auto emissions…. That’s a real WAG, because there are so many factors to control for, including how far back you trace the usage of fuel, i.e. To mine the ore with pick and shovel to put in a smelter to make steel, to make tools from the steel, to use the tools to make other tools and machines to generate electricity by burning natural gas or coal or fuel oil or uranium, and to transmit the electricity over a network made up of structures which were made from refined ore… And so on.

Eventually you have to make a lot of assumptions, and even the best of estimates are WAGs when you get down to it. My WAG, if done correctly, is 2 x 9235 pounds per capita per annum, which comes out to about 9.235 tons, which is still way below the Terrapass figures – but they use a lot more sophisticated analysis than I do.

For what it’s worth, the US Environmental Protection Agency says US transportation produced 27% of all US greenhouse gases in 2003, and 1.87 gigatons of CO2 equivalent. This would contain about 0.5 gigatons of carbon if it were all CO2, but ‘CO2 equivalent’ means they’re also including other greenhouse gases.

We need to put a lot of these figures on the Azimuth Project in a well-organized way. Or at least links to lots of data. Right now this information is spread all over the landscape. Of course I prefer world figures, but there’s also lots of data for individual countries.

JB said “By the way: how come I can afford to create a link to the original article, while the BBC and other mass media cannot? Is it really so bloody difficult? Isn’t it just basic good journalism?”

A guess, based on comments from other science bloggers: journals a have some sort of weird deal going on with the media, where the press release happens, and popular articles are written, well before the original article appears.

In this paragraph I will state in which journal the research will be published. I won’t provide a link because either a) the concept of adding links to web pages is alien to the editors, b) I can’t be bothered, or c) the journal inexplicably set the embargo on the press release to expire before the paper was actually published.

(Extra-ordinarily, many if not most of the “reader comments” are worth reading.)

How To Write Math Here:

You need the word 'latex' right after the first dollar sign, and it needs a space after it. Double dollar signs don't work, and other limitations apply, some described here. You can't preview comments here, but I'm happy to fix errors.